Gas generators with a shell-like lower part and an upper part screwed to it and with an igniter, propellant chamber, and filter means arranged between these two principal parts were described and represented in the relatively early European Patent Applications 12,626 and 12,627.
This design has obviously not proven to be successful, because material-positive connections, especially those brought about by friction welding or electron beam welding, are preferred in more recent applications, such as EP 180,408 A1 and DE 29,15,202 A1, in order to connect a lower housing shell with the upper part.
In the prior-art screw connections, the thread is on the outside, which is disadvantageous.
The prior-art welded connections are tight and compression-proof, but they require a considerable expense for manufacture.